A mass flow meter of this general type is known, for example, from the WO No. 85/05677. In that prior meter design, the measuring tube (shown in FIG. 4 of that publication) consists of a uniformly bent tube-piece which is helicoidally bent so that the two tube loops extend in a spiral path. The inflow and outflow ends of the tube are guided from the outside tube windings tangentially in opposite directions and are bent outside of the tube loops into a joint axle center where also takes place the mounting or clamping of the tubes on bearing blocks. This fastening results, to be sure, in a relatively favorable, almost exclusively torsional, stress at the two clamping sites. However, the great distance between the clamping sites requires a considerable mechanical expenditure for a stiffening device that exludes as much as possible external vibration effects. Such mechanical stiffening devices also require much space.
European Patent Application No. 86 200 575.8 describes a mass flow meter in which two ovally-bent tube loops, arranged approximately parallel to one another, as well as an inflow and outflow tube are welded to a connecting block provided with flow channels. This construction has, however, the drawback that the measuring tube is subdivided into four tube sections which have to be welded to the connecting block in an involved manner. These welding connections of the bent tube loops are weakened by the deformation forces arising upon oscillation of the tubes; indeed, in some cases, the connections can be destroyed. Furthermore, cracks or grooves caused by the welding can exclude that type of flow meter from certain application fields, e.g. for the food industry.